Some portable electronic devices such as a tablet terminal, a smartphone, and a laptop PC are equipped with a coordinate detection device called a digitizer tablet (hereinafter called a digitizer) as an input device or are connected with external interfaces. A digitizer is configured to allow a user to input data using a position indicator (electronic pen). One of the operating principles of the digitizer is based on electromagnetic induction. Such an electromagnetic induction-type digitizer includes a coil array disposed at a sensor panel that detects the position of the electronic pen based on magnetic flux of electromagnetic waves propagating between the sensor panel and the electronic pen. Such a digitizer allows a system to recognize hand-written letters and figures drawn on the sensor panel with the electronic pen.